THE PRINCIPLES OF BOTANY. 
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Lycopodales. — Vascular, spore-cases marginal, axillary, or radical, one 
or many celled. Spores of two sorts. 
Filicales. — Vascular, spore-cases marginal or dorsal, one-celled, 
usually surrounded by an elastic ring, spores of but one sort. 
Of these alliances Professor Lindley makes no less than 
eleven natural orders consisting of four classes, viz. Hepaticce, 
of which we shall speak of Equisetacece — Horsetails — Musci, 
Mosses — Lycopodales, Club-mosses, and Filicales as the best 
known types. 
Of these, the first group contains the Equisetacese, the 
genera and species of which, under the name of horsetails, 
are usually described as “ Fern Allies ,” but we quite agree 
that their affinities are rather with Marchantia , on account 
of the elaters to their spores, than with mosses or even ferns 
or club-mosses, to which they are not closely allied either by 
habit or structure. Horsetails are common to sandy pools 
and wet sandy loams in arable lands, and hence they are in- 
dicators of silicio- aluminous conditions. They are got rid of 
by draining and cultivation, but their decidedly siliceous 
composition makes it possible for some of their species to exist 
for along time even under garden cultivation, the Equisetum 
arvense being often a decided pest in both fields and gardens. 
The ashes of some species yield as much as half their 
weight of pure silica, and it is on this account that the plant 
is used for the purpose of polishing. In a medical point of 
view they are unimportant, though said to be diuretic and 
emmenagogue, in which latter character they may possess 
some of the qualities of the ferns, but it is questionable 
whether in this case the observed effects may not be in a 
measure due to the astringent and nauseating influence of 
the plant. 
Mosses are interesting to the botanist from their great 
variety in form, structure, and size. They seem to be made 
for occupying all space, and next to lichens to be everywhere 
the pioneers of the higher or floral vegetation. Professor 
Lindley has well observed, “ they are among the first vege- 
tables that clothe the soil with verdure in newly formed 
countries, and they are the last that disappear when the at- 
mosphere ceases to be capable of nourishing vegetation. The 
first green crust upon the cinders of Ascension consisted of 
minute mosses ; they form more than a quarter of the whole 
flora of Melville Island, and the blank and lifeless soil of 
New South Shetland is covered with specks of mosses 
struggling for existence. How they find their w’ay to such 
places, and under what laws they are created, are mysteries 
that human ingenuity has not yet succeeded in unveiling. 
